1. Field of the Invention
The present invention relates to an apparatus and method for producing a rapid time-related three dimensional image with a numerical profile of an object. More particularly, it involves projecting complex digitally based patterns of electromagnetic waves (e.g. light) or scanning laser beams(s) on to the object, photographing these patterns with a fast response digital camera, and rapidly calculating a dimensional map of the contours, edges, and openings of the object. In a previous patent application Ser. No. 10/966,095, filed Oct. 14, 2004 we described the general technique for carrying out the method. In this patent we extend this general technique to describe several different systems. One system uses a high intensity single flash projector(s) to obtain un-blurred 3d images of a moving or still object. The second system uses a series of projections to provide more information, and also to provide time evolution information.
2. Description of Related Art
In 1905, Albert Einstein, who at that time was a patent examiner in Zurich, developed the Special Theory of Relativity which emphasized the importance of considering time in addition to the three dimensions of space in describing the behavior of matter and energy. In accordance with this concept, creating three dimensional profiling images in a very short time period is very useful in order to record a plethora of fundamental dynamic observations in physics, chemistry, biology, microscopy, medicine, and engineering. It also has a particular application to identification procedures for security applications.
Stereoscopic photography was invented in the nineteenth century, and has been developed since then to create very colorful stereoscopic movies. In contrast, the development of stereoscopic profiling with accurate detailed measurements of three dimensional objects has been difficult to achieve. The development of digital photography and fast computation using fast digital processing has now provided the possibility of accurate stereoscopic imaging with detailed dimensional measurements of the contours of an object in real time.
Presently used techniques for non-invasive three dimensional imaging with digital detailing of an object utilize a variety of systems. One technique is the use of time of flight of a pulsed laser where by the distance from the laser to the object is determined by measuring the transit time of the laser beam. This procedure, described by Cameron, et al in U.S. Pat. No. 5,006,721 provides fairly accurate digital topographical data. A commercial version of the laser ranging system is manufactured by Cyrax Technologies and several other companies. While such systems provide good three dimensional data, they involve a quite costly apparatus because the time of flight must be measured to a few picoseconds, and the mirrors used to direct the laser beam as well as the mirrors used to route the reflected beam must be exact to a small division of a minute of arc. In addition, the scanning of a three dimensional object with a laser beam requires a considerable length of time, due to the fact that each incremental point on the surface of an object must be illuminated by the beam and the time of flight measured, resulting in a finite (and relatively long) time for all points to be illuminated and surveyed.
Another technique for non-invasive three dimensional imaging is the use of stereographic projections of a grid. This procedure, as described by M. Proesmans, et al. In U.S. Pat. No. 6,910,244, issued Jan. 21, 2003, describes the use of a projected grid for topographic imaging. They describe a grid projection with a camera directed to provide three dimensional imaging. The use of such relatively static methods does not provide for the real-time measurement of dynamic details needed for dynamically imaging and measuring surface contour dimensions of objects which have movement, such as a bridge or beam undergoing stresses and strains. As stated in their patent, their application is “aimed at showing and not measuring the object.”
Applications such as rapid engineering and reverse engineering with dynamic considerations of stress-strain relationships, measurements of flexure of mechanical and civil structures such as airplanes, vehicles, bridges, pipes, pipelines, steel tanks, autos and ships require very fast imaging techniques for which this invention is designed and applicable. In other applications as human body imaging where, due to walking, running, throwing, swinging, breathing and heart motion, it is important to consider the time aspect of imaging in order to acquire realistic measurements of the body. There is a need for such rapid imaging procedures in medical and sports an analyses, for example, in following the progress, and in determination of the efficacy of treatments of such diseases as osteoporosis and skin cancers as well as other skin and body medical and biomedical problems. There are many other industrial applications of this invention. The position and location of parts (of automobiles for example) on an assembly line can be measured quickly and accurately. The invention can also be used for wheel alignment. A major advantage of this procedure is that it provides better angular accuracy because hundreds of thousands of measurements are made instead of the relatively few measurements made with the earlier laser techniques. The fast acquisition time means images of moving wheels can be taken without blurring which leads to better accuracy because of better feature recognition. There are also many military and security applications from crime and forensic scene documentation to involuntary facial scanning to solving a jig saw puzzle: recognizing enemy assets from partial scans taken through trees and other opaque obstacles.